Efficacy of alcoholic plant extracts in controlling nymphs of the Jasmine whitefly (Aleuroclava jasmini)

Abstract

The jasmine whitefly, Aleuroclava jasmini (Takahashi), is an economically damaging pest affecting citrus cultivation in Iraq, necessitating the development of environmentally benign control alternatives to synthetic pesticides.  This study evaluated the insecticidal activity of alcoholic extracts from three medicinal plants: Piper nigrum (black pepper), Laurus nobilis (laurel), and Nerium oleander (oleander) against nymphs of A. jasmini under controlled laboratory conditions.  Alcoholic extracts were prepared using 97% ethanol via Soxhlet extraction for P. nigrum fruits and maceration for L. nobilis and N. oleander leaves. Three concentrations (1.5%, 2.5%, and 5.0% w/v) of each extract were tested on cucumber leaves naturally infested with A. jasmini nymphs. Mortality was recorded at 24, 48, 72, and 96 h post-treatment and corrected using Abbott's formula. Data were analyzed using factorial analysis of variance within a completely randomized design.  All extracts exhibited concentration- and time-dependent efficacy with significant variations in corrected mortality rates. N. oleander mean mortality of 22.38%, followed by P. nigrum (17.52%) and L. nobilis (17.03%). Notably, N. oleander at 2.5% concentration achieved the highest early mortality (35.20% at 24 h), indicating rapid knockdown potential. Peak mortality for most treatments occurred at 72 h post-treatment, followed by a significant decline at 96 h, suggesting limited residual activity.  These findings highlight the potential of botanical extracts as sustainable alternatives, particularly N. oleander, as eco-friendly alternatives for integrated pest management. However, formulation improvements are needed to enhance the stability and residual efficacy of P. nigrum and L. nobilis extracts for practical field applications.